Chiofalo B. et al., 2019
Athletic performance of a working dog is the result of a complex interaction between genetic, workout and nutrition but this last aspect is often underestimated and not properly formulated.
Physical activity causes the increase of energy consumption that changes in relation to the type, intensity, duration of work, and in relation to the environmental conditions in which the animal is working.
For these reasons the choice of diet is very important to improve animal performances and to maintain gastrointestinal tract health since utility dogs often suffer from gastrointestinal disorders consequent to stress derived from their life style (work and kennel conditions): using a food with highly digestible proteins can have beneficial effects on intestinal fermentative phenomena and, therefore, on the digestive capacity of the intestine itself.
On 2018 it was conducted a study in Sicily at the “Regional Centre Helen Keller of the Italian Blind and Guide Dog School Union” on 8 neutered adult Labrador retrievers with the aim of analyzing differences between nutrient digestibility and faecal characteristics of two different diets characterized by the absence of cereals or by the presence of conventional cereals.
Only healthy dogs were admitted to the study and for this reason they were preventively submitted to a physical examination, complete blood count, biochemical examination, and urine analysis; dogs admitted to the study were divided into 2 homogeneous groups for sex (half males and half females), age (17 ± 1 months), initial body weight (BW, 26.3 ± 1 kg) and body condition score (BCS, 4.5 ± 0.11).
The guide dogs for the blind were trained 3 times a week for three months. Each training session lasted approximately 60 min.
One group were fed with a commercial diet characterized by the absence of grain cereals (GF) and by a minimum quantity of carbohydrate from potato; whereas, the control group (CTR) received a super-premium pet food characterized by conventional grains such as carbohydrate source. All the diets were characterised by lamb meal as the main protein source. Diets were evaluated for dry matter (DM), organic matter (OM), and crude protein (CP); the acid-hydrolysed fat and total dietary fibre (TDF) content was determined.
The trial lasted 84 days, preceded by a 7 days of adaption period: the diet was given twice in a day in individual bowls.
PHYSICAL EXAMINATION
During the period of adaption, to exclude the presence of parasitic diseases, parasitological exams were performed. In detail, from each dog, a blood sample was collected and used for the diagnosis of leishmaniosis through immunofluorescence antibody test (IFAT) technique; rapid immune-chromatographic tests were also performed to search Ehrlichia canis, Anaplasma phagocytophilum, Borrelia burgdorferi and Anaplasma platys. In addition, all dogs were checked by copromicroscopical investigations before inclusion, and every 15 days from day 0 until the end of the test (total 7 copromicroscopical controls).
At day 28, 2 dogs belonging to the GF group resulted positive to the coccidia presence: they were properly treated and one week later, they turn into negative. From day 35, all dogs were negative to the controls until the end of the study. None positive dogs had symptoms related to the presence of parasites such as diarrhoea and or weight loss.
Weekly, to evaluate the performance of the studied dogs, from the day 0 to day 84, all dogs were undergoing physical examinations including:
- Mentation (level of consciousness);
- Posture and gait (watching the animal walk to exam area or to kennel);
- Hydration status – (evaluated from the elasticity of the skin and classified in “adequate”, “marginal” or “inadequate”);
- Rectal temperature (°C);
- Pulse rate (evaluating such pulse of femoral artery);
- Respiratory rate and breath character;
- Perfusion indicators (mucous membrane colour and capillary refill time).
At the same time, on each animal, the following parameters were evaluated: BW, BCS, muscle condition score (MCS), faecal consistency score (FCS) and feed intake.
The determination of BW was measured on fasted animals, in the morning at 09:00, by using a digital scale. Body condition score was evaluated by assigning a rating scale that ranged from 1 (too thin) to 9 (too heavy. Muscle condition score was assessed using a scale from 3 (no muscle wasting, normal muscle mass) to 0 (marked muscle wasting): the evaluation of muscle mass included the visual examination and the palpation over the temporal bones, scapulae, ribs, lumbar vertebrae, and pelvic bones. Faecal consistency score was evaluated by assigning a rating scale that ranged from 1 (dry stools) to 7 (liquid stool).
DIGESTIBILITY and FAECAL CHARACTERISTICS
Monthly, for each dog, total faecal output was collected, mixed, dried at 55°C and ground through a 2-mm screen. Composited faecal samples were analysed for DM, OM, CP and fat content, as described for diets. Apparent nutrient digestibility values were calculated using the following equation:
Apparent nutrient digestibility (%) = 100 x [Nutrient intake (g/d) – Faecal output (g/d)]/Nutrient intake (g/d).
From day 0, every month, fresh faecal sample were collected also for protein catabolite component analysis (ammonia, amines, SCFA, BCFA, phenols, and indoles).
RESULTS and CONCLUSIONS
The two diets compared were characterized by the following analytical parameters:
All the animals during the trial lost weight; this could be due to the training work for the service guide for the blind; but the most impressive weight loss was recorded in dogs of the CTR (-4.8kg), than the GF group (-1.0 kg). Moreover, the GF group showed better BCS and MCS than the CTR group while remaining in ideal values (score 4-5 out of 9). As regard the MCS (score 3 to 0), no significant differences in relation to the diet and time were observed. BCS and MCS are not directly related.
The fecal consistency score did not show significant differences between the two groups and the values, except for the 14-day CRT group, fell within the normal range (score 2 and 3). The quantity of faeces was influenced only by the diet over the whole period of the trial showing significant lower quantities in the GF group than those of the CTR group.
For what protein and fat digestibility concerned, higher values were recorded in the GF group than the CTR group showing that diet GF with high protein and low carbohydrate it’s more digestible than a commercial high carbohydrate dry diet and showing that GF diet is characterized by a less marked intestinal fermentation of carbohydrates.
Diet’s composition influenced quantity of nutrient catabolites in faeces: lower content of propionate and butyrate in effect were recorded in the faeces of the GF group. The similar content of the sum of organic acids in the faeces despite the higher protein content of the GF diet (39.24%, as-fed) than the CTR diet (24.40%, as-fed) could be due to the higher digestibility of the dietary protein in the grain free diet (+10%).
The composition of a diet in terms of protein and carbohydrate concentration, as well as the digestibility of the ingredients used, is able to influence the athletic performance of an animal.
The high-protein, low-carbohydrate dry diet (GF diet) offered higher apparent nutrient digestibility (+10% digestibility of protein and + 7% of fat) compared with the commercial high-carbohydrate dry diet (CTR), enabling dogs to use nutrients from the diet more efficiently and thus requiring less food (-13%) to satisfy their nutrient requirements, producing less excrement (-33%), and reaching a higher final BW (+8%) and a higher final BCS (+15%).
These results highlitgh how the GF diet appeared the nutritional plan most suitable for these animal not only for the training work done by these animals, with the increased nutrient and energy needs, but also for the gastrointestinal disorders consequent to stress coming from work and life in kennels which cause in the Labrador Retriever an unusual weight loss.